Pixelization of blended background image in BTB

Hi! How does one keep the background image blended to terrain from being pixellized? I've looked at some tracks and they have a much smaller background image, yet they don't show up pixelized when being driven on in rFactor. I've tried searching for an answer but am probably phrasing it wrong. Are there any settings in BTB for this or is it in a file I should edit manually? Thanks for any advice!

i guess threes a few ways, u can use smaller tiled background image, or a huge high res one..
or use a regular one and hide its bad (up close) pixels my blending in bump, or another texture that is tilled at at much small scale.

Use add and multa maps to get the close up detail.
Here is a perfect example, Up close and zoomed out. You can see nice detail up close and far out you can see nothing repeated, it looks very natural.

The green grass and the dead grass colour is from the background image which is a single 1024x1024 pixelated overhead image of the track with some editing to add certain shades, the grass detail is from the add and multa maps that are tiled every few metres.
Although you can use colour in add and multa maps, they can be just black and white.
Add for the sunny side of the grass blade and Multa for the dark side of the grass blade. It's similar to bevel in photoshop.
Anything black in an add map wont show up, anything white in a multa map wont show up.
Because add and multa maps aren't directly viewed, you can tile them pretty tightly and not see repetitiveness.

Seeing your Sears Point is what made me start this thread. I also looked at the BTB "Laser" tracks, Eastern Creek and Oran Park. I'll goof with multimaps and see what happens. I haven't experimented with them yet.

I live 75 minutes from Sears Point, I can't wait til you are done with it. Thanks again for the advice.

Thanks for the help Mianiak, I looked at your examples and applied them. Here's where I am at:

Unfortunately BTB crashed while saving my project last night (it made an incomplete project) and my only backup was done a few days before. All recovery efforts failed. I was 95% done. I still plan on releasing this track when I figure out how to modify individual GMT files.

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Excuse me for hoping a ride on you thread wagnerov but I think this question is a continuation.
I've been wondering, for a while, why my addon textures, especially grass based, always looked different against the default grasses and having seen your terrain work mianiak and read your comments I searched for more info. Came across a thread from 2009 between R Soul and woochoo which put it into perspective. Thought best way to learn is take apart a default grass, with multi & add, and put it back together. Did that but ended up with just the diffuse texture (thats what it looks like) in BTB. Sort of sparkles.
I have the 3 images - diffuse - multi & add loaded into XPacker and they are listed together in Textures. I made the latter 2 half size of the diffuse.I tried with alpha trans and chroma and I have saved textures in DXT3 and DXT5. What settings are used to get this all together please.